Computer vision has been used to analyze images from the real world for a variety of purposes. One example is to provide a natural user interface (“NUI”) for electronic devices. In one NUI technique 3D images of a user are captured and analyzed to recognize certain poses or gestures. Therefore, the user may make a gesture to provide input to control an application such as a computer game or multimedia applications. In one technique, the system models the user as a skeleton having joints that are connected by “bones” and looks for certain angles between the joints, bone positions, etc. to detect a gesture.
Such techniques work well as a NUI. However, some applications require more precise understanding and analysis of the user's motion.